HANSEN: THE ISOPODA. 115 



Habitat. The described pair were found in the branchial cavity of a speci- 

 men of Nematocarcinus agassizii Fax., from Station 3407 (Lat. 0° 4' S., Long. 

 90° 24' 30" W.), 885 fathoms. The swelling of the carapace is oblong, and 

 not very high. 



11. Munidion princeps, n. gen., n. sp. 



Plate IV. Fig. 3-ae; Plate V. Fig 1-1 d. 



Two females with their males were secured. 



a. Female. 



The body, when seen from above (Fig. 1), of an almost pyriform outline, 

 and not quite 1^ times longer than broad (the uropods not included). One 

 specimen has the right margin convex, — a " right " specimen ; the other is 

 a "left" specimen. 



Head. It is much broader than long and encircled posteriorly and on the 

 major part of its sides of the first thoracic segment ; the dorsal surface is some- 

 what convex, and the frontal border tolerably broad and bent conspicuously 

 upward ; the anterior margin is slightly convex. The antennulae (Plate IV. 

 Fig. 2) separated by a frontal plate ; they are of medium size, 13-jointed ; the 

 basal joint is comparatively large, the third extremely small. The antennae 

 are rather short, 3-jointed ; the basal joint is long and exceedingly broad, 

 almost triangular, with the expanded inner border overlapping the outer part 

 of the mandibles and the lateral angle of the labrum, the produced anterior 

 angle extends to the frontal plate and the second joint is inserted on the vertex 

 of the triangle ; the last named joint is short and slender, the third joint ex- 

 ceedingly small. The frontal plate is broadly triangular Avith obtuse vertex, 

 completely occupying the small space between the foot of the antennulse, the 

 anterior angle of the antennae, and the labrum. The labrum (c) scarcely of 

 medium size, somewhat broader than the hemi-cylindrical hypopharjmx. 

 Hypopharynx, mandibles {d), maxillulae, and maxillae need no special men- 

 tion. The left maxilliped is sho^vn in Figure 2 a ; the most interesting 

 character is that the palp has almost disappeared, as we see but a some- 

 what produced angle. The border behind the maxillipeds is very well 

 developed, with a number of small protuberances, and having on each side 

 two oblique slender processes, of which the inner is long, the outer very 

 long. 



Thorax. Ovarian bosses are developed on all segments ; they are very prom- 

 inent, most of them almost semi-globular (on the drawn specimens they are acci- 

 dentally — caused by pressure — more or less depressed on the right side of the 

 second to the fourth segment) ; in the three anterior segments they are large and 

 gradually decrease in size backward, the two posterior pairs almost petiolated, 

 the seventh pair small (in the small specimen the two posterior pairs are even 

 reduced to prominent, distally not swelled processes). The bosses do not oc- 

 cupy the sub-lateral part of the segments to its whole length, only the larger 



